The present invention relates to a colour picture display tube.
During the evolution of colour picture display tubes there have been many proposals for producing colour pictures using a single electron beam rather than three electron beams as is generally done in present day, commercially available colour picture display tubes. Generally these proposals have involved deflecting a high voltage beam onto a repeated pattern of phosphor strips or dots. Deflecting a high voltage beam requires high deflection voltages which would have to be switched at a high frequency and as a result this approach has not found commercial success.
British Patent Specification No. 1,458,909 dicloses a display tube which includes a channel plate electron multiplier which is scanned on an input side by a low energy electron beam. After current multiplication and focusing, the beam exiting from the multiplier is accelerated towards a phosphor screen. The channels in the electron multiplier are arranged in columns and between adjacent columns a single deflector electrode is mounted on the output face. Alternate electrodes are interconnected to form two sets of interdigitated selector strip electrodes. With this arrangement of electrodes, as the beam is scanned crosswise then at the exit side of the electron multiplier the electron beam leaving one aperture can be deflected left to right after which, the electron beam leaving an adjacent aperture in the same row can be subsequently deflected from right to left, and so on. In consequence the phosphor strips have to be arranged in a sequence P1, P2, P3, P2, P1, P2, P3 and so on. A disadvantage of such an arrangement is that it is not possible to correct electrically for small misalignments between the channel plate electron multiplier and the screen. Further, the colour resolution is impaired because the pitch of the P1 and P3 phosphors is twice that of the P2 phosphors.